改性麦麸吸附铟(Ⅲ)的性能研究

Adsorption Properties of Modified Wheat Bran for In( Ⅲ)

以酸性KMnO4为改性剂对麦麸进行改性,制备能够吸附In(Ⅲ)的生物质吸附剂。考察了改性剂中KMnO4与硫酸的浓度对改性效果的影响。改性效果随着KMnO4浓度的升高而提高,使用浓度为25 g·L-1的酸性KMnO4改性的麦麸对In(Ⅲ)有最佳的吸附效果。改性剂中硫酸的浓度对改性效果的影响呈现出先增大后减小的趋势,并且在硫酸浓度为0.3 mol·L-1时,吸附效果最佳。考察了溶液p H值、吸附时间、In(Ⅲ)浓度和温度等因素对改性麦麸吸附In(Ⅲ)的影响。结果表明:在初始p H为2.5的硫酸溶液中,改性麦麸对In(Ⅲ)有很好的吸附效果,且吸附在2 h内基本达到平衡;吸附过程是吸热过程,吸附符合Langumir吸附模型,为单分子层吸附,饱和吸附量能够达到23.65 mg·g-1。分别采用拟一级动力学模型及拟二级动力学模型对吸附动力学数据进行拟合。拟合结果表明拟二级动力学模型能够很好地描述改性麦麸吸附溶液中In(Ⅲ)的过程。动态吸附与洗脱时,流速为1.0 ml·min-1的条件下能够获得良好的效果,对吸附于饱和后的吸附剂上的In(Ⅲ)可用2 mol·L-1的盐酸进行洗脱,洗脱率达到96%。

Wheat bran was modified with KMnO4 in acidic solution to prepare biomass adsorbent for In（ Ill ） adsorption. The effects of concentrations of KMnO4 and sulfuric acid in modifier on modification were investigated, respectively. The modification effect in- creased as the concentration of KMnO4 increased, and when the concentration of acidic KMnO4 reached 25 g·L-1 , the modified wheat bran showed the favorable adsorption for In （ Ⅲ ）. The modification effect firstly increased and then decreased with the concentration of sulfuric acid in the modifier increasing, and the adsorption effect was optimum with the sulfuric acid concentration of 0.3 mol·L-1. The influence of factors such as the pH value of solution, adsorption time, the concentration of In（ Ⅲ ） and temperature on the adsorption of In（Ⅲ ） by modified wheat bran were investigated. The results showed that the optimum initial pH value for In（ Ⅲ ） adsorption on mod- ified wheat brans was 2, 5. The adsorption could reach equilibrium in about 2 h, The adsorption process was endothermic and the ad- sorption data was found in accord with Langmuir isotherm by monolayer adsorption. The maximum amount of saturated adsorption was 23.65 mg·g-1. The kinetics of adsorption In（ Ⅲ ） were fitted with Lagergren first order rate model and pseudo second order model, re- spectively. The kinetic data indicated that the adsorption of In （ Ⅲ ） with modified wheat brans was in a good agreement with the pseu- do-second order model. The flow rate of 1.0 ml.min-1 produced a good effect in the dynamic adsorption and elution experiments. In（Ⅲ） adsorbed in saturated adsorbent could be desorbed with 2 mol·L-1 hydrochloric acid solution and the elution ratio reached 96%.